1906 A Church of England Grammar School for girls and boys is established in Lambie Street, Cooma with Mr Maurice Henry Barnard as Headmaster.

1907 The equipment and goodwill of the Grammar School are sold for 17 pounds to the Reverend Charles Burgess, Rector of St Paul's, Cooma.

1908 Manaro Grammar School is established by Canon Burgess as a Diocesan foundation, with the same badge as CGS but with a different motto, Virtutem Doctrina Paret.

1926 Reverend William John Edwards is appointed Headmaster of Manaro Grammar School.

1927 An application is made to the Federal Capital Commission for 15 acres of land for the purpose of starting the Canberra Church of England Grammar School.

1928 Prime Minister, the Rt Hon Stanley Bruce, lays the foundation stone of the School on 5 December.

1929 A private company known as the Canberra Grammar School is incorporated and registered on 20 June. CGS starts operations on 5 February. The east wing and cloister are completed by September and the Boarders take up residence in Term 3.

1934 The Headmaster's residence is completed at a cost of 1,500 pounds.

1935 Work commences to complete the east side of the quadrangle with four new classrooms, four dormitories, masters' quarters, a dining room and kitchen. Bishop Ernest Burgmann dedicated the temporary Chapel.

1937 Dr Cyril Norwood, President of St. John's college, Oxford, and formerly Headmaster of Marlborough and Harrow, is present for the unveiling of stones set in the cloister walls. The stones came from the English public schools, namely Eton, Westminster, St Paul's, Charterhouse, Uppingham, Clifton, Tonbridge, Shrewsbury, Sherborne, Wellington, Rossall, Cheltenham, Repton and Radley.

1938 A tutorial system is introduced, which means that each member of staff is allotted eight to ten boys to care for. The building of the Dining Hall and kitchen block and Garran House begins.

1939 His Excellency the Governor-General, Lord Gowrie, opens the new buildings - Dining Hall, kitchen, library, and science laboratories. Lord Gowrie unveils a tablet recording the work of Mr P L Sheaffe in connection with the construction of the School oval.

1941 The temporary Chapel moves to a new site near the open-air theatre and re-built with an exterior facing of pine log off-cuts.

1947 The Reverend W J Edward resigns to take up a position with UNESCO in Greece. The Reverend Jock Gardiner becomes the Acting Headmaster.

1948 Canon D A Garnsey commences his duties as Headmaster at the beginning of the Third Term.

1950 The Reverend K S Crossley is appointed first Master-in-Charge of the Junior School.

1957 The Bishops of New York and Chicago as well as Bishop Burgmann plant trees along the upper section of the main driveway.

1958 The Headmaster, the Canon Garnsey, is elected the fifth Bishop of Gippsland. An appeal for a new Chapel is launched. Four new classrooms are built at the northern end of Garran House. Work on the War Memorial Gymnasium nears completion. The Headmaster is invited to become a member of the Headmasters' Conference of the Independent Schools of Australia.

1959 An Old Boy, Mr P J McKeown is appointed the third Headmaster of CGS, at the beginning of 1959.

1960 His Excellency the Governor-General, Sir William Slim, opens the War Memorial Gymnasium on 2 August. Thirty-one plaques in memory of Old Boys killed in the World Wars are placed over the entrances to various rooms by the Old Boys' Union.

1962 On 19 April, the Prime Minister, the Rt Hon R G Menzies, opens the new science and administration wing that completes the quadrangle. In addition to the science facilities on the first floor, the new building provides a staff common room, office space and a music room.

1963 On 23 September His Excellency the Governor-General, the Viscount De L'Isle, opens the new Junior School. The award of House Colours for excellence in academic excellence, games and Winter Projects are initiated.

1965 The new Senior Boarding House (Blaxland) opens on 8 August.

1968 A student Council is formed, with the Captain of the School, David Smythe, as Chairman, and 18 members, consisting of one boy elected from each year, and two from each House.

1971 The Craft Centre is opened by the Minister for Education, the Hon Nigel Bowen, QC MP and Stage II of the Junior School is opened by the Minister for Education, the Hon David Fairbairn, on 1 June.

1973 The first School Counsellor, Mr R Ritter, is appointed.

1975 Girls are accepted into the Infants' Schools.

1976 The Dr W J Edward's History Centre is opened by the Vice-Chancellor of  The ANU, Professor D A Low, and dedicated by Bishop D A Garnsey, the second Headmaster of the School, on 15 October.

1978 A new compulsory service scheme, involving Third Form boys in a year of service with the Scouts, the Cadet Unit or the School Service Group, is introduced. The Prime Minister, the Right Honourable J M Fraser, presents the prizes and unveils a commemorative plaque to mark the beginning of the Jubilee Year.

1979 The Governor-General, Sir Zelman Cowen, opens the Music Centre on 3 May, Jubilee Year.

1980 Junior School Hall opens.

1981 Pre-School opens

1983 South Science Block opens.

1985 Mr Paul McKeown retires after 27 years as Headmaster.

1986 Mr Tim Murray appointed the fourth Headmaster. Paul McKeown opens the McKeown Wing on 20 May.

1988 Bi-Centenary celebrations. The whole School travels to St Saviour's Cathedral, Goulburn to record their singing of Australian Christmas music. New Maintenance Centre opens.

1989 Diamond Jubilee celebrations. Boarders' Common Room opens

1990 Dr Peter Ellyard opens Resource Centre and Burton Theatre on 27 July.

1991 Craft Centre renamed the Design Centre and extensions completed.

1992 War Memorial Hall foyer opens including extensions to the Music Department and refurbishment of the War Memorial Hall.

1993 Mexican Ambassador to Australia, HE Senor Enrique Buj-Flores. opens the International Centre. Extensions to Junior School are completed.

1996 Robert de Castella opens Health and PE Centre on 17 September. The replica of the Manaro Grammar Lynch Gate opens.

1997 Refurbishment and naming of Junior School Hall as The John Lingard Hall, and Multi Media Centre, Philip Spelman Sculpture and Chapel Terraces are opened on March 12. The Peace Window is dedicated on 16 September. Junior School Art Room opens.

1998 The Roy Morrow and Shelagh Haines Foyers for Maths and English are opened on 21 March. A Time Capsule, to be opened on the 100th Birthday of the School, is set in place in the Shelagh Haines Foyer. Mr Tim Murray retires as Headmaster in June and Mr Simon Murray (no relation) is appointed as fifth Headmaster in July.

1999 70th birthday celebrations. Strategic Directions and School Master Plan are published and the school-wide optic fibre network is begun.

2000 Professor Don Aitkin, Vice Chancellor of the University of Canberra, opens the Early Learning Centre.

2001 Centenary of Federation celebrations nationwide and at CGS, with student exchanges from all states and territories, exhibitions at School; whole school attends Parliament House celebration on 9 May. Reconstruction work begins on the Main Oval.

2002 The Governor-General, Dr Peter Hollingworth, lays foundation stone of Performing Arts Centre on 27 October. First Cricket match on the new Main Oval: Headmaster's XI V the Old Boys.

2003 Old Boy and ABC personality, James O'Loghlin, opens Performing Arts Centre on 28 February. First production: All Stops Out by Michael Gow in the Tim Murray Theatre, named after the Fourth Headmaster, Mr Tim Murray. School community donates $25,000 to the Galilee School, partially destroyed in the 18 January bushfires.

2004 75th Anniversary of the School. Celebrations include the 75th Anniversary Ball in the Great Hall of Parliament House with music legend, James Morrison; a two day Arts Festival, and the installation of a new organ in the Chapel, a gift of the P&F to the School.

2005 Strategic Directions 2005-2009 completed.

2006 School decides to stay with NSW High School Certificate after review of alternative credentials. Staff complete extensive Year 7-10 Curriculum review. New website is launched.